This song was actually released under Clairity's new project called 7Chariot, I have updated the artist, added a video and fixed the typo in the title. The issue is now there's a duplicate so please merge:
(the lyrics to the original are incorrect, and the lyrics on the duplicate are correct).

Songfacts says "The song was written by the Chainsmokers and Coldplay band members. It was produced by Chainsmokers with frequent collaborator DJ Swivel."

Also "This anthemic tune is a collaboration between the Chainsmokers duo and the British band Coldplay. The dance floor-ready song was premiered with a live performance by both groups at the 2017 BRITS Awards "

If the Chainsmokers and Coldplay have performed together only once and have only that song, there's no point in having a page called Coldplay & The Chainsmokers because they aren't a duo or anything. The song can be on one artist's page (if the other one is the featuring artist) or on both artists' page.

If the Chainsmokers and Coldplay have performed together only once and have only that song, there's no point in having a page called Coldplay & The Chainsmokers because they aren't a duo or anything. The song can be on one artist's page (if the other one is the featuring artist) or on both artists' page.

Either way is fine with me. But maybe we should make sure all moderators are in agreement so there is consistency.

If the Chainsmokers and Coldplay have performed together only once and have only that song, there's no point in having a page called Coldplay & The Chainsmokers because they aren't a duo or anything. The song can be on one artist's page (if the other one is the featuring artist) or on both artists' page.

Either way is fine with me. But maybe we should make sure all moderators are in agreement so there is consistency.

To my understanding that's how it is. But if they had released an album together and that song was on it, then it should be under Coldplay & The Chainsmokers. You said both have released the song on their own albums, so then it can be on either one's page (or on both, I guess, if neither is called a featuring artist - it's still good to link the entries together though).
I'm not sure are there some exceptions or something, maybe others can say more about that. I have, for example, seen Eurovision song entries (duets?) added on artist pages where they are the only song. Maybe that's a bit different case.